1. Field to Which the Invention Pertains
This invention pertains to the box forming art and more particularly to the art of forming a box from a flat blank which has been appropriately cut and scored.
Paperboard boxes and particularly corrugated paperboard boxes are generally formed from a flat blank which has been appropriately cut and scored so as to facilitate the formation of a box. Because users of corrugated paperboard boxes may consume thousands of boxes daily, machines have been developed which will accept a flat paperboard blank and automatically form such a blank into an open box which is then discharged from the machine.
Although a wide variety of such machines have heretofore been developed, a particularly difficult problem is presented when it is required to automatically form a box having walls of more than a single thickness. More specifically, in the formation of such a box there will rise the requirement that large parts or flaps of the blank will have to be folded in such a manner that they are superimposed adjacent to other, equally large flaps or panels. The problem that is presented is distinct from the problem of folding a blank to form a box wherein the overlapping parts of the resulting box are relatively small. In the latter situation, it is relatively straight forward to secure the desired folding action since the parts of the blank to be folded into overlapping relation are relatively small and therefore multiple folding steps can be performed during a single motion of the blank. For example, if the parts of a blank which are to be folded into overlapping relation are relatively small, such parts may easily be folded while other major sections of the blank are also being folded. However, when it is required to form a box having large overlapping portions, the shear size of the overlapping portions may cause interference problems when the folding steps are performed.
Another problem which has faced the box forming art is the difficulty of forming a large box and then transforming the shape of the formed box so as to obtain a configuraton which will allow dense packing of the formed box whereby a plurality of formed boxes may be transported at a low cost. Once again, the box forming art discloses machines for collapsing previously formed boxes provided that such boxes are relatively small or are constructed of relatively lightweight materials such as folding carton paperboard.
The instant invention supplies a solution to these problems in that, in accordance with this invention, a corrugated paperboard blank of substantial size may be automatically formed into a box wherein at least one pair of walls have a double thickness. Further, the practice of this invention permits the automatic formation of such a box followed by the automatic collapsing thereof.
Thus, this invention pertains to a method and apparatus whereby a flat blank may be formed into a box wherein at least two walls of the box have a double thickness and whereupon the formed box may then be collapsed.
2. Prior Art
Relevant prior art U.S. Pat. Nos. are 2,249,859, 2,138,766, 2,279,534, 3,309,970 and 2,248,535. These patents appear to reflect the state of the art to which this invention pertains. Further, these patents suggest that the methods and apparatus disclosed therein have limited utility and that they are generally applicable only to blanks for forming relatively small boxes or blanks constructed of relatively lightweight and flexible paperboard such as folding carton paperboard. For example, the method and apparatus disclosed in U.S. Pat. No. 2,138,766 to MacDonald is said to be useful in connection with the collapsing of "Brightwood" boxes which, as those skilled in the art are aware, are open-top trays generally made of lightweight paperboard.
Similarly, it will be seen that in U.S. Pat. No. 2,279,534 there is disclosed a method and machine for making and collapsing paperboard boxes in the form of a shallow, open-top tray.
U.S. Pat. No. 3,309,970 discloses a method and apparatus for flat-folding bottom sealed cartons. However, as may be seen upon a review of this patent, the size of the apparatus disclosed therein is substantial and in order to secure the desired result a plurality of serially acting mechanisms are required, e.g. link-driven, folding mechanisms and a plurality of conveyor belts.